Global warming impacts virtually all biota and ecosystems. Many of these impacts are mediated through direct effects of temperature on individual vital rates. Yet how this translates from the individual to the population level is still poorly understood, hampering the assessment of global warming impacts on population structure and dynamics. Here, we study the effects of temperature on intraspecific competition and cannibalism and the population dynamical consequences in a size-structured fish population. We use a physiologically structured consumer-resource model in which we explicitly model the temperature dependencies of the consumer vital rates and the resource population growth rate. Our model predicts that increased temperature decreases resource density despite higher resource growth rates, reflecting stronger intraspecific competition among consumers. At a critical temperature, the consumer population dynamics destabilize and shift from a stable equilibrium to competition-driven generation cycles that are dominated by recruits. As a consequence, maximum age decreases and the proportion of younger and smaller-sized fish increases. These model predictions support the hypothesis of decreasing mean body sizes due to increased temperatures. We conclude that in size-structured fish populations, global warming may increase competition, favor smaller size classes, and induce regime shifts that destabilize population and community dynamics.
- EURASIAN PERCH
- INDIVIDUAL GROWTH
[Ohlberger, Jan; Edeline, Eric; Vollestad, Leif Asbjorn; Stenseth, Nils C.] Univ Oslo, Dept Biol, CEES, N-0316 Oslo, Norway; [Edeline, Eric] Univ Paris 06, UMR 7618, Ctr Natl Rech Sci, Lab Biogeochim & Ecol Milieux Continentaux, F-75230 Paris 05, France; [Claessen, David] Ecole Normale Super, UMR 7625, Lab Ecol & Evolut, Environm Res & Teaching Inst, F-75230 Paris 05, France
Ohlberger, J (reprint author), Univ Oslo, Dept Biol, CEES, POB 1066 Blindern, N-0316 Oslo, Norway.
- Ecologie et évolution, UMR7625
- Institut d'écologie et des sciences de l'environnement de Paris (IEES), UMR7618